from lab05 import *

## Extra Questions ##

## Linked Lists ##

def interleave(s0, s1):
    """Interleave linked lists s0 and s1 to produce a new linked
    list.

    >>> evens = link(2, link(4, link(6, link(8, empty))))
    >>> odds = link(1, link(3, empty))
    >>> print_link(interleave(odds, evens))
    1 2 3 4 6 8
    >>> print_link(interleave(evens, odds))
    2 1 4 3 6 8
    >>> print_link(interleave(odds, odds))
    1 1 3 3
    """
    "*** YOUR CODE HERE ***"

def filter_list(predicate, lst):
    """Returns a link only containing elements in lst that satisfy
    predicate.

    >>> lst = link(25, link(5, link(50, link(49, link(80, empty)))))
    >>> new = filter_list(lambda x : x % 2 == 0, lst)
    >>> print_link(new)
    50 80
    """
    "*** YOUR CODE HERE ***"

## Trees ##

def add_song(t, song, category):
    """Returns a new tree with SONG added to CATEGORY. Assume the CATEGORY
    already exists.

    >>> indie_tunes = tree('indie_tunes',
    ...                  [tree('indie',
    ...                    [tree('vance joy',
    ...                       [tree('riptide')])])])
    >>> new_indie = add_song(indie_tunes, 'georgia', 'vance joy')
    >>> print_tree(new_indie)
    indie_tunes
      indie
        vance joy
          riptide
          georgia

    """
    "*** YOUR CODE HERE ***"

def delete(t, target):
    """Returns the tree that results from deleting TARGET from t. If TARGET is
    a category, delete everything inside of it.

    >>> my_account = tree('kpop_king',
    ...                    [tree('korean',
    ...                          [tree('gangnam style'),
    ...                           tree('wedding dress')]),
    ...                     tree('pop',
    ...                           [tree('t-swift',
    ...                                [tree('blank space')]),
    ...                            tree('uptown funk'),
    ...                            tree('see you again')])])
    >>> new = delete(my_account, 'pop')
    >>> print_tree(new)
    kpop_king
      korean
        gangnam style
        wedding dress
    """
    "*** YOUR CODE HERE ***"